Sift flour, baking soda, and salt together. Set aside.
In a mixing bowl, cream together the butter, brown sugar, and sugar until well blended. Add vanilla, egg, and egg yolk and mix until smooth.
Add dry ingredients just until blended. Stir in the chocolate chips. Refrigerate batter for at least 1 hour.
Preheat oven to 325 degrees. Line baking sheets with parchment paper. Drop cookie dough, ¼ cup at a time, onto cookie sheet (I rolled each into a ball).
Bake for 15-18 minutes until edges are golden. Cool on sheets for 2 minutes; transfer to cooling rack.
Recipe by Simple, Sweet & Savory at https://www.simplesweetsavory.com/big-chewy-chocolate-chip-cookies/